Automatic wrapping machine



Feb. 25, 1969 F. F. TREIBR AUTOMATIC WRAPPING MACHINE Sheet Filed Oct. 24. 1965 Feb. 25, 1969 F. F. TREIBER 3,429,098

AUTOMATIC WRAPPING MACHINE Filed OCT.. 24. 1965 K m Q Sheet of9 qb@ Q N Feb. 25, 1969 F. F11-Rensen 3,429,098

AUTOMATIC WRAPING MACHINE m QS] www @N NWN Sheet w QN QN Filed Oct. 24. 1965 Feb. 25, 19699 F. F. TREIBER AUTOMATIC WRAPPING MACHINE Filed Oct. 24. 1965 Il IIIILIIF m 130 Nlll g 6,6 I Z3 ,11g 2 133 Fel. 25, 1969 F. F. TREIBER AUTOMATIC WRAPPING MACHINE Sheet Filed Oct. 24. 1965 F. F. TREIBER AUTOMATIC WRAPPING MACHINE Feb, 25, 1969 Sheet Filed Oct. 24. 1965 QQ www. Qu

Feb. 25, 1969 F. F. TREIBER AUTOMATIC WRAPPING MACHINE f Sheet 7 of 9 Filed Oct. 24. 1965 F. F. TREIBER Feb. 25, 1969 'AUTOMATI C WRAPPING MACHINE Sheet g of 9 Filed Oct. 24. 1965 Sheet Filed Oct. 24. 1965 AQNK United States Patent O "ice '18 Claims ABSTRACT F THE DISCLOSURE An automatic wrapping machine having package forming means extending along a path and with structure for preliminarily placing wrapping film around the package 4including an in-feed conveyor beneath the path, a transfer platform adjacent the in-feed conveyor and movable toward and away from the in-feed conveyor to receive a package from the in-feed conveyor and then move to a spaced location whereby the package elevator can move downwardly to a position adjacent the transfer platform and the in-feed conveyor and with the elevator having clamping means for the leading edge of the Wrapping film to draw the film downwardly whereby movement of the package onto the elevator will cause preliminary wrapping of the film about the package. The package elevator is movable upwardly and the package movable from the elevator into said path to complete the wrapping of the film about the package. The wrapping film 'is positively controlled at all times with positive gripping means on the elevator and with structure to cut off the film and at the same time insure the insertion of the new leading edge into the gripping means. Additionally, better control of the film is provided by a concave roller for support of the supply roll of film and positive cycled means which maintain the film taut as the package elevator moves upwardly with the package thereon. Additionally, the pressure and time of pressure `application and final sealing of the package by pressing it on a hot plate are variably controlled by pressure roller means movable to different positions to provide the variable control.

This invention relates to automatic package wrapping equipment and more particularly to automatic wrapping machine as well as the methods performed and package made by the machine.

An object of this invention is to provide an automatic package wrapping machine wherein successive packages are each wrapped in an individual length of film with the film length being cut from a film web and of a size as determined by the package size and wherein successive packages can enter an entry end of the machine and are wrapped and delivered from the opposite eXit end of the machine, with the machine including a package elevator and means for receiving a package at the entry end of the machine and conveying the package across the path of the elevator to a position for coaction with the package elevator.

Other objects of the invention are to provide an automatic package wrapping machine as defined in the preceding paragraph in which an -in-feed conveyor at the entry end of the machine conveys successive packages to a transfer platform which can move to a position adjacent the in-feed conveyor and in a space which is cyclically occupied by the package elevator and which retracts to a position whereby the package elevator can move to the cyclically occupied position and la package is then transferred from the platform to the elevator to initiate wrapping of film about the package; in which the elevator is mounted for movement between an upper generally horizontal position and a lower slightly tilted position between the in-feed conveyor and the platform with the tilted position requiring a lesser space between the 3,429,098 Patented Feb. 25, 1969 conveyor `and platform to shorten the path of movement required for the platform and to reduce the vertical space required for the elevator; in which means are provided for moving the package elevator through its cycle of movement with means responsive to a jam of the elevator either in up or down movement to release the drive of the elevator and discontinue operation of the machine; in which the package elevator engages a leading edge of the continuous film and pulls the lm down as the package elevator moves to Ia position adjacent the transfer platforrm to place a length of the film in the path of a package to be transferred from the platform to the elevator with the film leading edge being positively gripped by gripping members on the elevator and with the film being positively positioned within the gripping members as a part of the film cut-off cycle during the wrapping of a preceding package; and in which structure is optionally useable for obtaining positive release of the gripping members from the leading edge of the film as a package is placed onto the elevator and in response thereto to reduce the pull on the film by the package when a softproduct is being packaged.

Further objects of the invention are to provide an automatic package wrapping machine in which a package elevator operates as defined in the preceding paragraphs and wherein the film is supplied to the elevator from a supply roll mounted by means providing a peripheral drive for the supply roll and the drive occurring intermittently in response to the size of a loop of film and the peripheral drive providing a constant rate of feed off of film from the roll and wherein the supply roll is mounted by roller structure providing constant centering of the roll; wherein a back feed roll is disposed between the elevator and the supply roll and positioned in a loop of film to maintain the film under some tension and which operates to draw back film as required as the elevator is elevated to maintain a fairly tight wrap of the film about a package on the elevator which is being wrapped and said back feed roll moving with the elevator at all times so that the elevator can repeatedly cycle with back feed of the film if no package should be advanced onto the elevator.

Still further objects of the invention are to provide a wrapping structure and method performed thereby for providing a more tightly sealed package in which the ends of the wrapping material are folded partially under the package with the ends reversed on themselves and heat sealed to effect sealing of the end portions of the film to each other as well as to other portions of the film wrapped about the package to effect a doubled back seal which is particularly desirable with film coated with a heat scalable material on one side only so there can be no open path through the film layers from the interior to the exterior of the package.

Further objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIG. 1 is a front elevational view of the automatic Wrapping machine showing a package positioned at the entry end of the machine;

FIG. 2 is an end el'evationalAview looking toward the right-hand end of the machine as shown in FIG. v1;

FIG. 3 is a vertical section taken generally along the line 3 3 in FIG. 1 and with drive chains omitted for clarity;

FIG. 4 is a plan view of the machine with the overhead conveyor omitted for clarity;

FIG. 5 is a vertical section on an enlarged scale taken generally along the line 5 5 in FIG. 4;

FIG. 6 is a fragmentary plan View of the package elevator on an enlarged scale and showing a portion of the film cutter associated therewith;

FIG. 7 is a fragmentary side elevational view of the structure shown in FIG. 6 looking toward the lower end thereof as viewed in FIG. 6;

FIG. 8 is an end elevational View of the package elevator looking toward the right-hand thereof as viewed in FIG. 6;

FIG. 9 is a plan detail view of a portion of the under folding structure for the package shown generally in FIG. 4;

FIG. 10 is a vertical section through a package prior to completing the wrapping thereof and taken generally along the line lil-10 in FIG. 9;

FIG. 10-A is a fragmentary elevational View of a down-folding plow;

FIG. 11 is a fragmentary vertical section taken generally along the line 11-11 in FIG. 9 and showing a package as the under folding operation begins;

FIG. l2 is a view similar to FIG. 11 taken generally along the line 12-12 in FIG. 9;

FIG. 13 is a view similar to FIG. 11 showing the package more fully formed and taken generally along the line 13-13 in FIG. 9;

FIG. 14 is a view of the package after it has left the folding station shown in FIG. 13 and prior to heat sealing of the film layers together with the space between layers shown slightly enlarged for clarity;

FIG. 15 is the first of a series of views showing the sequence of operation of the automatic wrapping machine;

FIG. 16 is a view similar to FIG. 15 showing a succeeding step in the wrapping cycle;

FIG. 17 is a view similar to FIG. 15 showing a third step of the wrapping cycle;

FIG. 18 is a view similar to FIG. 15 showing a fourth step in the wrapping cycle;

FIG. 19 is a detailed side elevation of the package holddown structure shown in one operative position in full line and a second operative position in broken line;

FIG. 20 is an end elevational view of the structure shown in FIG. 19;

FIG. 21 is a view of latch structure for the film loop control roller and the snubbing roll;

FIG. 22 is a fragmentary view of the package guiding structure disposed along one side of the machine;

FIG. 23 is a fragmentary elevational view of the back feed roll and its mounting and actuating structure; and

FIG. 24 is a side elevational view of a` modified form of package elevator.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail an embodiment of the invention together with a modification thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

The wrapping machine is shown generally in FIG. 1 and includes an in-feed conveyor, indicated generally at A, at one end of the machine which receives a package of meat or the like having a tray or board on which the prod-uct is placed, as indicated generally at B, with the in-feed conveyor advancing the product onto a transfer platform, indicated generally at C, which can move between the retracted position shown in FIG. 1 and an advanced position adjacent the in-feed conveyor A when it is to receive a package. After the package is received on the platform C the platform returns to the position shown in FIG. 1 for transfer of the package to an elevator indicated generally at D, with the initial wrapping occurring as the package is a-dvanced onto the elevator and further being accomplished as the elevator is elevated from a lower position to the position shown in FIG. 1 where banding the wrapping film about the ptackage is completed as the package is moved substantially off the elevator. An overhead conveyor system, indicated generally at E, advances the package through a wrapping station, indicated generally at F, in FIG. 4, where the end sections of the wrapping material are folded progressively under the package as shown in FIGS. 11-13. The film layers at the underside of the package are then heat sealed on a hot plate, indicated generally at G, and the package is then discharged :from the machine at an exit end opposite from the entry end.

The sequence of operation can be best understood generally by reference to FIGS. l5 to 18 which show steps of the operating cycle and a description with reference to these figures is given prior to a detailed description of the structure of the machine. As shown in FIG. 15, a package B advances from the initial position on the in-feed conveyor A to a position on the transfer platform C which in broken line is shown in its advanced position adjacent the in-feed conveyor. During this time the elevator D is in its upper position to provide an unobstructed path for movement of the transfer platform C. Following delivery of the package onto the transfer platform, the platform returns to its right-hand retracted position, as shown in full line in FIG. 15, to provide a gap between it and the in-feed conveyor A so that the elevator D can descend to an inclined position in the space as shown in FIG. 16.

During the lowering movement of the elevator film H is drawn downwardly by the gripping mechanism on the elevator to extend vertically across the path of a package which is pushed olf the transfer platform C onto the elevator, as shown in FIG. 17. This action of pushing the package into the film results in release of the film from the gripper structure on the elevator to have the leading edge 0f the film underneath the package as shown in FIGS. 10 and 17 and with the adjacent film extending over the package. The elevator D then ascends to its upper horizontal position shown in FIG. 18 to substantially complete the wrapping of the film about the package and as the package is pushed off the elevator D the wrapping is completed and a hot plate seals the overlapped lm at the underside of the package, forming an intial tack seal with opposite ends of the film extending from the package as shown in FIG. l1. As shown in FIG. 18, the film wrapped about the package is cut off from the supply length thereof by cutting mechanism in part carried by the elevator and simultaneously the leading edge of the film supply is inserted within the gripping structure on the underside of the elevator. As will be noted in FIG. 18, a succeeding package has been placed on the transfer platform C and the platform has returned to its retracted position awaiting the next descent of the elevator D for wrapping of the next package.

F Im feed The film is supplied to the wrapping machine from a roll of film indicated generally at R which is supported at the periphery thereof by a pair of relatively large driven rollers -10 and 11. The rollers 10 and 11 are selectively driven as required from a driven shaft 12 having a gear 13 (FIG. 3) thereon which is connected by a chain 14 to a sprocket on the shaft of roller 11 for rotating the roller in a clockwise direction as viewed in FIG. 1. A chain 15 at one end interconnects rollers 10 and 11 so that roller 10 is driven by roller 11 and both driven rollers rotate in a clockwise direction for delivering film from the supply roll R when required. The drive of sprocket 13 is controlled by a magnetic clutch 16 (FIG. 3) with the engagement of the clutch under the control of an idler or dancer roller 17 mounted on spaced pivotal arms 18 and positioned within a loop of the film H. The clutch 16 is controlled by a limit switch 19 (FIGS. l5 and 16) mounted on the frame of the machine whereby the normally closed limit switch is held open when the loon of lm is relatively large as shown in FIGS.

1 and 15 and is permitted to close when the loop shortens as shown in FIG. 16. The operation of switch -19 is controlled from an actuator plate i carried on the lower end of one of the idler supporting arms 18. When the loop shortens to the extent shown in FIG. 16, the limit switch 19 has closed and the clutch 16 engaged to drive the rollers 10 and 11 to add additional film to the loop in which the idler 17 engages.

In order to keep the roll R centered relative to the machine the roller 11 is contoured as shown in FIG. 2 to have inclined outer sections 11a and 11b defining a generally concave contour for the roller which results in maintaining the supply roll centered relative to the machine since the supply roll will resist climbing up either of the inclines 11a and 11b and will remain in a position in which the forces acting on the supply roll R are balanced. This action requires that the roller 10 be straight.

The loop of film in which the idler 17 rests is defined by a pair of rollers 21 and 22 xed to the frame of the machine and extending transversely thereof. The film travels from roller 22 over a pair of rollers 23 and 24 spaced from each other to provide a gap therebetween in which an intermediate film loop can be formed and in which a back-feed roll 25 rests to exert tension on the film intermediate the loop at the supply roll and the wrapping station having elevator D. The film then passes between rollers 26 extending transversely of the frame and the lm partially wraps about one or the other of these during the wrapping operation. For additional support of the lm through the machine, a pair of support plates 27 and 28 are mounted to the frame with the plate 27 spanning the space between the rollers 22 and 24 and the plate 28 spanning the space between the rollers 23 and 26. In order to prevent retrograde movement of the film a non-rotating snubbing roll 29 is mounted on a pivoted arm 30 disposed at an angle whereby film can readily travel from right to left as viewed in FIG. 15 but any tendency for movement in the opposite direction will be prevented by the wedge action of the snubbing roll 29.

To facilitate threading the film initially through the machine in setting up the film supply a latch structure is provided including a latch member 31 which as shown in FIG. 21 is pivoted by means of a pivotal shaft 32 to a position to engage a reduced end 33 of the idler roller 17 to latch the idler roll 17 in an extreme position of rotation adjacent the rollers 21 and 22 with a centrally located finger 34 positioned to engage the arm 30 of the snubbing roll 29 to raise the snubbing roll at the same time as the idler roll 17 is latched with the result that film can be easily threaded through the machine. When the latch is released by slight clockwise pivoting from the position shown in FIG. 21 the idler roll 17 is free to move in a clockwise direction and snubbing roll 29 to return to engagement with the lm. Pivotal movement of the latch 31 is restrained to a limit position by the upper end thereof engaging a stop bar 35.

I n-feed conveyor The in-feed conveyor A extends from the left-hand end of the machine as viewed in FIG. 1 and embodies a platform having central slot 41 through which a single pusher 42 can travel with the pusher 42 being fastened to an endless chain 43 passing about a drive sprocket 44 and an idler sprocket 45. The in-feed conveyor also has a pair of package guides 46 and 47 (FIG. 4) extending along the length thereof and which are adjustable toward and away from each other dependent upon the size of package to be wrapped. The in-feed conveyor is timed relative to the cycle of the remainder of the wrapping machine whereby the pusher 42 will deliver a package to the transfer platform C when the latter is in position adjacent the in-feed conveyor platform 40 to receive the package.

Transfer platform The transfer platform C embodies a platform base 50 shown in FIGS. 1, 3 and 15 to 18 which is generally square in plan view and which can move between the full line and broken line positions shown in FIG. l5. The platform base is supported from beneath by a longitudinally extending rod 51 and a transversely spaced bar 52 for movement between limit positions. A downwardly depending collar 53 is movable on the rod 51 and upper and lower rollers 54 are movable on the bar 52 with the collar and rollers being mounted on brackets depending from the platform base 50. The transfer platform is operated in a cycle by a cam arm 55 which is pivotal on a shaft 56 extending across the machine near the bottom thereof and having a cam follower roller 57 engageable in a suitable cam track of cam 57C mounted on a cam shaft 60. The upper end of the arm S5 is connected to a bracket 58 which supports the mounting collar 53 through an adjustable linkage 59 extending from the upper end of the arm 55. In one cycle of operation the' cam shaft 60 is rotated through one revolution and the drive cam 57C for the cam arm 55 cycles the arm to move the transfer platform C in an operating sequence of movements as previously described in connection with FIGS. 15-18.

The transfer platform C has a pair of package guides associated with it which align with the package guides 46 and 47 of the in-feed conveyor A. As shown in FIG. 3, these guides comprise spaced apart upright elongate plates 61 and 62 which are interconnected for movement with the package guides 46 and 47 by structures subsequently to be described whereby rotation of a single handle will adjust the machine for handling differing package sizes. Each of the package guides 61 and 62 are similarly mounted and constructed. The package/guide 61 has front and rear transverse plates 63 `and 64 which have a rod 65 extending therebetween which is movable in a collar 66 fixedly connected to a depending bracket 67 which is connected to a frame structure for accomplishing lateral adjustment of the package guides. Since the guides 61 and 62 must move with the transfer platform C in its movements the movement is permitted by the movable mounting of the rod 65 in the collar 66 and the movement is cause by providing each of the guide plates 61 and 62 with a depending roller 68 and 69, respectively, which engage in a guide track extending transversely of the platform and which is formed by a pair of bars 70 secured to the platform. This causes the movement of the side guides with the platform while permitting their lateral adjustment by the rollers 68 and 69 being movable in the guide track formed by the bars 70.

The transfer platform C also has a package pusher 71 which overlies the platform base 50 and is cycled to be in a rearward position as shown in FIG. 15 in full line when a package is received on the transfer platform and subsequently to push a package off the transfer platform onto the elevator D as shown in FIG. 17. The pusher 71 is suspended over the platform base 50 by a laterally extending arm 72 which extends toward the back side of the machine where it connects with a longitudinally extending bar 73 which is guided for movement longitudinally of the machine from the back frame panel 74 by a plurality of Vertical and horizontal guide rollers 75a shown in FIG. 18. The bar 73 is connected to a vertical pla-te 75 at the rear of the machine which extends upwardly to connection with a block 76 which, as shown in FIG. 3, can move along a frame mounted rod 77. The block 76 has an arm 77a extending toward the center line of the machine and having a short arm 78 at a right angle thereto extending toward the entry end of the machine with a further arm 79 extending to the center line of the machine and having a downwardly angled pusher for pushing a package off the elevator D as described hereinafter.

The movement of platform pusher 71 and the elevator pusher 80 is derived from a cam arm 81 pivotal on the lower transverse shaft S6 and which has a cam follower roller S2 engageable in the groove of a cam 82e mounted on the cam shaft 60. The upper end of cam arm 81 is connected to the vertical plate 75 through a connecting linkage 83. In one cycle of operation the cam arm 81 causes simultaneous package advancing movement of the platform pusher 71 and retracting movement of the elevator pusher 80 and then retracting movement of the platform pusher 71 and package advancing movement of the elevator pusher 80.

Package elevator The package elevator D embodies an elevator base 85 which is generally rectangular in plan view which operates at a wrapping station between an upper package discharge level as shown in FIG. 18 where the elevator is generally horizontal and a lower package receiving position at which the elevator is in an inclined position to receive a package from the transfer platform C as shown in FIG. 17. The elevator is mounted for movement between the positions on a four arm linkage system having upper arms 86 and lower arm 87 at front and rear of the machine with the lower arms 87 being the power arms and afxed to a transverse rotatable shaft 88 extending from front to rear of the machine as shown in FIG. 3 and having a cam arm 89 atiixed thereto having a cam follower roller 90 engageable in a cam track of cam 90e mounted on cam shaft 60.

The lower power arms 87 each connect to plates 91 near the lower end thereof with there being a plate depending from each side of the elevator base 85. As a safety feature, the ends of the arms 87 are yieldably connected to the elevator base plates 91 in the manner shown in FIG. 18 whereby a jam of the elevator in either direction of movement will result in turning off power to the machine until the jam is corrected. This structure includes a roller 92 at the end of each of the arms 87 engageable in a central notch in a slot 93 at the lower end of the plates 91. If the elevator should resist following the power arms 87 at any time in either direction the roller 92 can shift in the slot 93 with the result that a switch 94 will be disengaged by the roller 92 to open the power circuit for the machine. The switch 94 is mounted on an arm 95 xed to one of the plates 91 and a fairly strong spring 96 is connected between the arm 95 and the roller 92 to cause the roller to remain in the notch in the slot 93 during normal operation.

The upper arms 86 are merely follower and guiding arms and are pivotal on stub shafts 97 at the front and rear of the machine. The arms intermediate their ends have collars 98 rotatably mounted on the stub shafts 97 and extensions 99 of the arms 86 are each provided with an abutment plate 100 as shown particularly in FIG. 23 which coacts with the opposite ends of the back-feed roller 25. The back-feed roller has reduced diameter sections at opposite ends thereof forming a pair of guide pins one of which is shown at 101 in FIG. 23 for guiding the back feed roller in up and down movement in a pair of slotted plates 102 at the front and rear of the machine. The roller is free to descend under gravity as permitted by the position of the arms 99 and is positively elevated by the abutment plates 100 as the arms 99 move up. Through these interconnections the back feed roller 25 is caused to cycle in timed relation with the package elevator D whereby as the elevator is descending the backfeed roller 25 is positively raised and as the elevator D is ascending the back-feed roller 25 is permitted to descend to maintain the film taut as it is being wrapped around a package. This also causes back-feed of the film if no package is present.

The relationship of the lengths of arms 86, 97 and their pivot axes results in inclination of the elevator when in the lower position so that, as shown in FIGS. 16 and 17, the elevator can be positioned between the in-feed conveyor A and the transfer platform C with a reduction in the required amount of movement of the transfer platform C. More specifically the transfer platform C does not have to move backward a distance equal to the width of the elevator as viewed in FIG. 16 due to the inclined orientation thereof which reduces the distance and therefore the time required for movement of the transfer platform C.

The elevator base has a pair of package guides 103 and 104 associated therewith which guide a package while on the elevator and which also function to tuck the film at the rear corners of the package as it is advanced from the transfer platform C onto the elevator D. These package guides and tuckers are relatively thin in height and overlie the elevator base 85 as shown particularly in FIGS. 7 and 8. These package guides are simultaneously adjusted for lateral spacing along with the guides 46 and 47 of the in-feed conveyor and guides 61 and 62 of the transfer platform C. This guiding is accomplished by having the forward ends of the guides each provided with a roller 105 which is movable in an upright channel 106 which extends downwardly from a block 107 to connect with a guide of the in-feed conveyor. The rollers 10S each extend from a block 105e which is transversely movable on a bar 105b extending across the rear of the elevator. The block 107 is mounted on a pair of vertically spaced transverse shafts with the shaft 108 being a guide shaft and the shaft 109 being threaded and operable from an end of the machine to be rotated. Reverse threading at opposite ends of the shaft causes the blocks 107 at said opposite ends to move either toward or away from each other to obtain lateral spacing of the guide structures previously described and also of the underfolding plow structure and guiding structure at station F to be described subsequently.

The package elevator has a pair of movable lingers 110 and 111 at the front side thereof which are movable between a lowered position beneath the level of the surface of the elevator base S5 and an upper position blocking the front of the elevator to hold a package on the elevator during elevation thereof from the position shown in FIG. 17 to the upper position. The lingers 110 and 111 are fixed to a rock shaft 112 extending across and beneath the elevator base 85 for rocking movement with the rock shaft. The lingers 110 and 111 are urged upwardly by a spring 113 (FIG. 7) engaging an arm 114 affixed to and extending from the rock shaft 112 with the movement being limited by an .abutment screw 115 secured to one of the elevator mounting plates 91. The fingers 110 and 111 must be depressed when the elevator D is in the lower package receiving position as shown in FIG. 16 and also in its upper position as shown in FIG. 18 to permit ingress and egress of a package relative thereto. This action is caused by a lever bar 116 affixed to an end of the rock shaft 112 which has an end 117 engaged by a pin (not shown) affixed to the interior of a front frame member 118 whereby as the elevator reaches its upper position the pin is contacted by the upper surface of the lever bar end 117 to rock the fingers 110 and 111 downwardly. When the elevator reaches its bottom position the opposite ends of the lever bar 116 iS engaged from beneath by another pin (not shown) on the frame member 118 to again rock the lingers downwardly out of obstructing relation with the travel of the package.

The package elevator has a package pusher block 120 mounted on the upper side thereof and extending for a height sufficient to substantially engage a package through the front plate 121 thereof Iwhich engages the trailing edge of a package on the elevator at all times and which functions to hold the film around the package during the wrapping operation as shown in FIG. 17. The pusher block is engaged by the package pusher 80 to discharge a package from the elevator as shown in FIG. 18. The block overlies a slot 122 in the elevator base 85 and is movably secured to the elevator by means of a bolt 123 passing therethrough and connected at its lower end to a plate 124 captured beneath the slot 122 and with a spring 125 on the bolt exerting downward pressure on the block to cause the block 120 to frictionally engage the elevator base 85 so that the block is restrained but free to move as external forces are applied to it.

The package pusher performs the important function of gripping the leading end of the film to the package as the package advances from the position of FIG. 16 to that of FIG. 17 in moving onto the elevator so that the film 'will be released from a film gripper to be described with the leading edge disposed under the package as shown in FIG. 17 and also shown in FIG. 10. It is a characteristic of the machine that the leading edge of the film will extend across beneath the package along the same line regardless of the package size since it is a constant length of film which extends from the package pusher to the film gripper.

The package elevator D also has mounted along the edge thereof and beneath the base 85 a transversely extending knife member 130 which coacts with a cyclically movable knife 131 movably mounted on the frame of the machine and cycled in a manner later to be described.

The elevator also has film gripping structure for gripping the leading edge of a film with this structure including an upper gripper member extending transversely of the elevator and defined by the under surface of the knife blade 130 carried by the elevator. The other part of the gripping structure includes a transversely extending plastic rib 132 mounted at the ends of a pair of spaced arms 133 and 134 which extend beneath the elevator and are rotatably journalled on the shaft 112 by spaced bearing blocks, one of which is indicated at 135. The gripping member 132 is urged against the knife member 130 by means of a spring 136 connected to the rear end of the lever arm 133 as shown in FIG. 7.

A film tucker in the form of a rectangular plastic bar 140 is positioned beneath the movable knife 131 and movable therewith whereby as the length of film wrapped about the package is cut off from the film supply the new leading edge is inserted in between the gripping members 130 and 132 by the tucker bar 140. As shown in FIG. 6, the tucker bar 140 is substantially aligned with the cutting edge of the cutter 131 at the center line of the machine so that the tucker 140 will extend into the space between the grippers during the cut-off operation for the film. The tucker bar 140 will cam open the gripping members against the action of the spring 136 connected to the mounting arm 133 and the film will be retained between the gripping members as they are caused to close by the spring and as the tucker bar is withdrawn because of the relatively slippery nature of the material used in forming the tucker bar. Alternatively, the tucker bar could be suitably coated.

The operation of the elevator in handling the film can now be more completely described with reference to FIGS. to 18 wherein it will be seen that in FIG. 15 the leading edge of the film H has been inserted between the gripping members. The elevator D then lowers to the position shown in FIG. 16 with the film being drawn downwardly by the gripping members on the elevator. At this same time the back-feed roller 25 is elevated through the upper mounting arms 86-99 of the elevator to remove the restraint of this roller as the film is drawn down. In FIG. 17, the package is shown as having moved onto the elevator and engaging the package pusher 120 with the film being released from the gripping members 130 and 132. In FIG. 18, the film has been completely wrapped around the package and the package is departing from the elevator with the film about the package being cut off by the cut-off knife 131 coacting with knife blade 130 on the elevator and at the same time the new leading edge of film is inserted between the gripping members for the next operation.

Knife and tucker The knife blade 131 and tucker bar 140 are mounted on a transversely extending mounting member which at each of its ends is mounted to a block 146 secured to a rod 147 which is movable within a pair of fixed guide blocks 148 and 149 (FIG. 5). The rod 147 is actuated by a cam arm 150 fixed to a shaft 151 extending transversely of the machine and rockably mounted therewith with a further cam arm 152 having a cam follower roller 153 coacting with a slot in a cam 153C mounted on the cam shaft 60. The upper end of the cam arms 150 are each connected to their respective guide rod 147 through an adjustable link 154 and a bracket 155 attached to the guide rod. The cam 153e is related to the other cams whereby to advance the knife and tucker bar when the package has in part moved off the elevator as shown in FIG. 18.

Package completion Up to this point structure has been described to initially band a rectangular sheet of film about a package as cut off from a supply of film and with the amount of film required for the package being automatically determined by the size of the package itself since as the package moves onto the elevator and the elevator rises, the requisite amount of film will be drawn from the film supply loop. As the banding of the article is completed by movement of the elevator to the position shown in FIG. 18 the back-feed roller 25 maintains the film taut about the package because of its downward movement as the elevator ascends with the weight of the roller being controlling as to the tautness of the film about the package.

As the package leaves the elevator the portion of the film adjacent the cut-off line is caused to move under the package and overlap the leading edge of the film as shown in FIG. l0 in which the leading portion is shown at 160 and the overlapping portion is shown at 161. The overlapped portions of the lm are then heat sealed together by the package being moved onto a hot plate 162 as the package leaves the elevator.

An overhead conveyor mechanism E subsequently to be described picks up the package resting on the hot plate 162 and then advances the package through a plow station F to complete the packaging.

As the package is brought up by the elevator to the upper position the lengths of film extending beyond the ends of the package are brought up 4beneath guide rails and 171 which as shown in FIG. 4 extend for substantially the entire length of the machine and a portion is shown in greater detail in FIGS. 9 and 10A. Each of these guide rails 170 and 171 have a downwardly inclined section 172 adjacent the heat sealing plate 162 whereby the upper film section 173 is drawn down about an end of the package as shown in FIG. 11 into contact with the lower film section 174. rl'he package is then advanced by the overhead conveyor mechanism E to advance the film sections 173 and 174 into an entry opening 175 between a plow member 176 and a reactive plow member 177. The plow member 176 is sloped inwardly toward the center line of the machine to progressively move the film section underneath the package as shown in FIGS. 12 and 13 with the reactive plow member 177 causing the fiaps to reversely fold backwardly onto themselves to form a doubled back fold of the sections 173 and 174 as shown in FIG. 14. A bottom plate 178 has an upturned end 179 whereby the doubled back yfilm sections can be brought up against the bottom of the package and to the level of a final heat seal station to be described.

The plow structure performs several distinct lfunctions and results in a package having a better seal than those heretofore known particularly with film having a heat sealing coating on only one side thereof which is the exterior surface of the film about the package. An important function is in drawing the film tightly across the package by having the reactive plow member 177 form resistance to underfolding of the lm section which tightly draws the film about the package. It will also be noted that drawing the upper film section 173 down to the lower section 174 results in an offset of these sections whereby the low section 174 extends beyond the upper section 173. As seen in FIG. 14, when the final heat seal occurs the upper surface of the exposed portion of section 174 can contact the coated side of the portion of section 173 thereabove to eectively seal the two sections together and avoid any air passages from the exterior to the nterior of the package. The seal is further enhanced |by having adjacent portions of section 173 both of which would be coated, engage each other for sealing.

Added novel results, regardless of the iilm used, are that the underside of the package is clearly visible to permit easy reading of printed matter, such as recipes, on the bottom of the packaged material; also, if a transparent meat tray is used, then the underside of the meat on the tray is visible.

The nal heat seal station G is shown in FIGS. l and 4 and embodies a hot plate 185 enclosed within a movable belt 186 of material, such as Teon, which permits free movement of the package over the hot plate. After leaving the hot plate, the package is discharged from the exit end of the machine.

Means are provided for effectively sealing the underfolded section of the package including pressure members for the package including a pair of endles belts mounted one on each of the side guides 170 and 171 for adjustable movement thereof with the remainder of the guides previously described. Each of these belts 187 is mounted on a pair of grooved rollers 188 and 189 which are rotatably mounted on a bar 190` pivotally connected at one end thereof to a plate 191 which is pivoted at its upper end by a pin 192 to a mounting plate 193 secured to the adjacent side guide. The rollers are constructed of relatively heavy material so that pressure can `be exerted through the endless belt against a package to insure that a good heat seal is effected. If quite soft materials are in the package, it is possible to reduce the amount of force exerted by the pressure means easily by pivoting the arm 190 to an upper position shown in broken line in FIG. 19 in which the weight of roller 188 is effectively removed from the system by having the support bar 194 rest on the top of the mounting plate 193. The bar 194, as shown in FIG. 20, also controls the lower position of the belt by engaging either the side guide 171 or 172.

If only rollers 188 and 189 were used, then a roller could fall into a vacant part of the package and loosen the film. The use of the belts around the rollers reduces this action.

Overhead conveyor The overhead conveyor E is continuously driven and embodies a frame above the wrapping station and plow station F with a series of chain carried paddles 200 which as shown in FIG. 1 travel in an arcuate path at one end of their travel to come down behind a package resting on the hot plate 162 and advance the package through the plow station F, the heat sealing station G, and out of the machine. The paddle that picks up the package on the hot plate 162 is not interfered with by the package pusher block 120 on the elevator D since the elevator D will already have descended and left a package resting on the hot plate.

More specically, the overhead conveyor has a pair of side plates 201 and 202 which mount chain sprockets 203 and 204 about which a chain 205 passes. Each paddle 200 has a pair of pins carrying rollers 206 at the opposite ends movable in lower tracks as shown in FIG. 2 and also movable in upper tracks formed by plates 207. The orientation of the paddles is controlled by a linkage S pivoted to the upper end of the paddle arm at 209 and having rollers 210 movable in the tracks in trailing relation with the rollers 206 of the paddle members.

Drive mechanism The drive is obtained from a motor 220 which through a gear reduction unit (not shown) drives a sprocket 221 which through a chain 222 drives a sprocket 223 on the cam shaft 60. The cam shaft 60 has a sprocket 224 aixed thereto which through a chain 22S drives a sprocket on a shaft 226 carrying the previously referred to sprocket 44 for driving the conveyor chain 43 of the in-feed conveyor A.

The shaft 12 of the supply roll drive is driven from the shaft 60 through a chain 227 engaging a sprocket 228 on the cam shaft 60 land a sprocket 229 on the shaft 12 (FIG. 3).

The overhead conveyor E is driven from the shaft 12 through reduction gears 230 and 231 with the latter gear being on a shaft 232 having a sprocket 233 which through a chain 234 drives a sprocket 235 (FIG. 2) and through a connected sprocket 236 drives a sprocket 237 by chain 238 which is on ya shaft 239 connected to the sprocket 204 of the overhead conveyor. An idler 240 is provided to take up slack in the chain 238.

Side adjustment The side adjustment to the guide structures previously described can be derived from rotation of the threaded shaft 109 at the entry end of the machine which through a chain 250 passing about the threaded shaft 109 and `a second threaded shaft 251 (FIG. 22) results in a variation of the spacing between the guides on the in-feed conveyor A, the transfer platform C and the guides 170 and 171 which carry the plow members 176 and 177 `as well as the pressure belts 187. Also adjusted at the same time are the plow guide members 103 and 104 on the elevator D.

Operation The initial step in the operation is for an operator to place a package of meat or the like on the in-feed conveyor A and the pusher 42 advances the package onto the transfer platform C which is in its advanced position with the elevator D in its upper position. With the package then on the transfer platform C, the transfer platform returns to its withdrawn position to provide a space in which the elevator D can descend to the inclined position shown in FIG. 16 with the grippers 130 and 132 drawing the leading edge of the film downwardly to a level beneath transfer platform C. The platform pusher 71 then advances the package onto the elevator as shown in FIG. 17 to start the wrap of the film about the package and drawing the leading edge of the film from the grippers 130 and 132. The elevator D then begins its ascent to bring the film around the package with the lm being maintained taut by descent of the roller 25 as permitted by movement of the elevator arms 86-99. When the package reaches the upper position, the iilm has been brought around the package and the package pusher block is then advanced by the package pusher 80 to advance a major part of the package onto the hot plate 162. The elevator then begins its descent to receive the next package and the overhead conveyor E has a paddle 200 sweep downwardly to the rear of the package and move the package continuously through the plow station F and then onto the hot seal plate at station G and then exit the package from the machine. In the event that a different length of package is to be wrapped, it may be necessary to change the supply roll R to a different width lilm which can readily be accomplished by latching up the dancer roller 17 and the snub roller 29 and then threading a nelw film through the machine. The only other operation required is that of adjusting the spacing between the various side guides which can be achieved by rotating the threaded shaft 109 from either the front or back of the machine by a suitable handle.

It will be seen that the machine may repeatedly cycle without a package and in the event a package is not delivered to the machine by the in-feed conveyor A, the machine can continue a cycle with the leading edge of the lrn remaining gripped between the gripper members 130 and 132. There will be no harmful slack created in the film because the idler roll or back feed roll is caused to cycle in timed relation with the elevator.

Additionally, there is no possibility of improper handling of the film since there is no loose leading edge at any time. As the length of film wrapped about a package is cut olf, the leading edge of the next section of film is simultaneously placed between the grippers 130 and 132.

A modification in the film gripping structure is shown in FIG. 24 in which parts similar to the previous embodiment have been given the same reference numeral with a prime affixed thereto.

At some times a very soft material may be in the package being wrapped and it is desired to avoid pressure on the packaged material as might be caused in drawing the leading edge of the film from the film grippers on the elevator. Accordingly, the modification shown in FIG. 24 provides for positive opening of the film grippers 130' and 132' fwhen a package enters onto the elevator D.

This structure includes a cam 300 on the underside of the package pusher block 120 which when moved across the elevator by entry of a package onto the elevator engages a cam surface 301 at the upper end of a pin 302 pivoted at 303 to a block 304 rotatably mounted on a shaft 112. The arm 302 is prevented by an abutment surface 305 on the block from pivoting when the cam 300 engages therewith in rearward movement of the pusher 120 with the result that as the package moves onto the elevator the arm 302 is lowered to open the -ilm grippers by lowering the gripper 132. When the package pusher moves in the opposite direction, the arm 302 is free to pivot about its pivot 303 to permit the pusher to return to the right side thereof as viewed in FIG. 24.

The foregoing structure only operates in response to the presence of a package so that in the event there is no package the machine can still continue to cycle repeatedly without releasing the grip on the leading edge of the film.

I claim:

1. In an automatic wrapping machine, a frame, means on the frame for conveying a package along a path leading to an exit end of the machine, plow means disposed along said path to fold film extending from the ends of the package to the underside thereof comprising, a first plotw member adjacent the end of the package to draw the upper lm section down across the end of the package, a second plow member to progressively fold the film sections under the package as the package moves along said path and a third plow member extending along beside the second plow member to place a reverse bend in said lm sections to double back said sections onto themselves, and means for thermally securing said film sections to each other and to the remainder of the film, and means for receiving a package at an end of the machine opposite from said exit and initially wrapping a length of flm from a supply roll around the package prior to the package entering said path comprising, an in-feed conveyor at the package entry end of the machine and at a level beneath said path, a transfer platform at the level of said in-feed conveyor, means for moving said transfer platform between a position adjacent the in-feed conveyor to receive a package from the in-feed conveyor and a position remote therefrom, a package elevator movable between a lower position adjacent said transfer platform Nvhen the latter is in said remote position and an upper position at the level of said path, means on the elevator for releasably holding the leading end of a film web, and means for transferring a package from the transfer platform to the elevator in its lower position while simultaneously moving the package into the lm and subsequently completing the :wrap by raising the elevator to its upper position.

2. In an automatic wrapping machine as defined in claim 1, first guide means on the n-feed conveyor for laterally guiding a package, second guide means on the transfer platform for laterally guiding a package, means on the elevator for tucking the film around the back corners of the package and laterally guiding the package, and spaced apart brackets :movably mounted on said frame, each of said brackets mounting the aforesaid guide means and the plow means for one side of the package.

3. In an automatic Wrapping machine as defined in claim 2 in which the distance between the in-fced conveyor and said transfer platform when the latter is in its remote position is less than the width of said elevator, and means mounting the elevator for movement to have the elevator generally horizontal in the upper position thereof land inclined in the lower position to have at least an edge thereof adjacent the transfer platform and the opposite edge overlying said in-feed conveyor.

4. In an automatic wrapping machine as defined in claim 2, means for moving said elevator between upper and lower positions including a drive connection which is releasable upon restraint imposed on the elevator in either direction of movement, and switch means positioned to sense said release of the drive connection `for stopping of said machine.

5. In an automatic wrapping machine, a frame, means on the frame for conveying a package along a path leading to an exit end of the machine, plow means disposed along said path to ifold lm extending from the ends of the package to the underside thereof and means for receiving a package at an end of the machine opposite from said exit and initially wrapping a length of film `from a supply roll around the package pritor to the package entering said path comprising, an in-feed conveyor at the package entry end of the machine and at a level beneath said path, a transfer platform at the level of said in-feed conveyor, means for moving said transfer platform in a path generally coplanar with the surface of the transfer platform between a position adjacent the in-feed conveyor to receive la package from the in-feed conveyor and a position remote therefrom, a package elevator movable between a lower position adjacent and between said infeed conveyor and transfer platform when the latter is in said remote position and an upper position at the level of said path, and means for transferring a package from the transfer platform to the elevator in its lower position while moving the package into the lm and completing the wrap by raising the elevator to its upper position.

6. A wrapping machine as defined in claim 5, in which the package is sealed on a hot plate, a frame member, pressure means for pressing a package against said hot plate including an endless belt, a pair of wheels about which said belt extends, a pivoted arm rotatably mounting said wheels, and means mounting lsaid arm for pivotal movement between a first position in which both wheels exert their weight on the package through the belt and a second position supported by the frame member in which the wheels are at opposite sides of the frame member and one wheel has a counterbalancing effect on the other wheel which presses the package.

7. In an automatic wrapping machine as defined in claim 5, first guide means on the in-feed conveyor for laterally guiding a package, second guide means on thc transfer platform for laterally guiding a package, means on the elevator for tucking the hlm around corners of the package and laterally guiding the package, and spaced apart brackets movably mounted on said frame, each of said brackets mounting the aforesaid guide means and the plow means for one side of the package.

'8. In an automatic wrapping machine as defined in claim 5, in which the distance between the in-feed conveyor and said transfer platform when the latter is in its remote position is less than the depth of said elevator, and means mounting the elevator for movement to have the elevator generally horizontal in the upper position i thereof and inclined in the lower position to have at least an edge thereof adjacent the transfer platform and the opposite edge overlying said in-feed conveyor.

9. In an automatic wrapping machine as defined in claim `8, in which the means mounting said elevator includes a pair of laterally spaced pivoted drive arms, a pair of laterally spaced pivoted guide arms above said drive arms, said arms being related to each other by length and pivot axes to provide said horizontal and inclined dispositions, said drive arms being mounted to the elevator by means defining elongated slots with the normal connection being intermediate the length of the slots, and switch means positioned to sense movement in said slots upon the occurrence of a jam for stopping of said machine.

10. In an automatic wrapping machine, means for conveying a package along a path leading to an exit end of the machine, plow means disposed along said path to fold film extending from the ends of the package to the underside thereof, and means for receiving a package at an end of the machine opposite from said exit and initially wrapping a length of film from a supply roll around the package prior to the package entering said path comprising, an in-feed conveyor at the package entry end of the machine and at a level beneath said path, a transfer platform at the level of said in-feed conveyor, means for moving said transfer platform between a position adjacent the in-feed conveyor to receive a package from the in-feed conveyor and a position remote therefrom, a package elevator movable between a lower position adjacent said transfer platform when the latter is in said remote position and an upper position at the level of said path, means on the elevator for releasably holding the leading end of a film web, means for transferring a package from the transfer platform to the elevator in its lower position while moving the package into the film, a backfeed roller disposed in a loop of film in `advance of said elevator, means for raising and lowering said elevator, and means operatively connected to said elevator to cycle said back-feed roller in timed relation with said elevator whereby raising of the elevator further urges the film about the package and the film is maintained relatively taut by lowering of the back-feed roller.

11. In an automatic wrapping machine, means for Wrapping a length of film around a package prior to cutting of the film from a web of film comprising, means mounting a supply roll of film, means guiding the web of film to a package wrapping station, an elevator at said station movable between an upper position and a lower level, means on said elevator for releasably gripping the leading edge of the film to draw the film across the entry side of the elevator as the elevator moves to said lower level including a pair of gripper members, means for pushing a package into said film while moving the package onto said elevator at said lower level, said elevator in moving r to its upper position wrapping the film around the package, and means adjacent the elevator upper position cyclically operable to cut the length of film about the package from the Web and positively inserting the leading edge of the film into said releasable gripping means including a tucker bar movable to a position between said gripper members.

12. An automatic wrapping machine as defined in claim 11 in which said elevator has a package supporting surface, a rst knife blade fixed to said elevator and extending along an edge of said elevator at a level beneath said surface and wherein one of said gripper members is positioned immediately beneath said blade, and said film cutting and inserting means includes a second knife blade coacting with said first knife blade and said tucker bar is of relatively slippery material and located beneath and movable with said second knife blade into said position between said gripper members to accomplish the film insertion.

13. In an automatic wrapping machine, means for wrapping a length of film around the package prior to cutting of the film from a web of film comprising, means for supplying a continuous length of film, means guiding the web of film to a package wrapping station, a member at said station movable between two positions, means on said member for releasably gripping the leading edge of the film to draw the film across the entry side of the member as the member moves to a package receiving position, means for pushing a package into said film while moving the package onto said member, said member in moving away from the package receiving position wrapping the film around the package, a back-feed roller disposed in a loop of film in advance of said wrapping station, and means moving said feed-back roller in timed relation with the member whereby as the member moves to its package receiving position the back-feed roller is moved up to avoid restraint on the film and as the member moves from the package receiving position the back-feed roller moves down to back feed the film and either assist in tightly wrapping the film around the package or maintain the film relatively taut if no package has moved onto the member.

14. In an automatic wrapping machine, a frame, means on the frame for folding film extending from the ends of the package to the underside thereof, and means for wrapping a length of film around the package prior to cutting of the film from a web of film comprising, means mounting a supply roll of film, means on the frame guiding the web of film to a package wrapping station, an elevator at said station movable between an upper position at the level of said film folding means and a lower level, means on said elevator for releasably gripping the leading edge of the film to draw the film across the entry side of the elevator as the elevator moves to said lower level, means for pushing a package into said film while moving the package onto said elevator, said elevator in moving to its upper position wrapping the film around the package, a back-feed member disposed in a loop of film in advance of said wrapping station and means moving said member in timed relation with the elevator whereby as the elevator moves down to its lower level the member is moved up to avoid restraint on the film and as the elevator moves up the member moves down to back feed the film and either assist in tightly wrapping the film around the package or maintain the film relatively taut if no package has moved onto the elevator.

15. In an automatic wrapping machine, a frame, means on the frame for folding film extending from the ends of the package to the underside thereof, and means for wrapping a length of film around the package prior to cutting of the film from a web of film comprising, means mounting a supply roll of film, means on the frame guiding the web of film to a package wrapping station, an elevator at said station movable between an upper position at the level of said film folding means and a lower level, means on said elevator for releasably gripping the leading edge of the film to draw the film across the entry side of the elevator as the elevator moves to said lower level, means for pushing a package into said film while moving the package onto said elevator, said elevator in moving to its upper position wrapping the film around the package, said supply roll mounting means including a pair of spaced apart rollers on which the supply roll rests, drive means for said rollers including a selectively engageable clutch, and an idler roll mounted in a loop of film for controlling the operation of the clutch, one of said rollers being generally concave and of a width to have inclined outer sections directly engage beneath and support the supply roll to continuously maintain said supply roll centered on said rollers.

16. In an automatic wrapping machine as defined in claim 15 a check member pivotally mounted on the frame and engageable with the film to prevent retrograde movement thereof, and latch means for latching both said idler roll and check member in inoperative positions for threading of film through the machine.

17. In an automatic wrapping machine, means guiding a web of lm to a package wrapping location, an elevator at said location movable between an `upper position and a lower level, means on said elevator for releasably gripping the leading edge of the lm to draw the lm across the entry side of the elevator as the elevator moves to said lower level, means for pushing a package into said film while moving the package onto said elevator, said elevator in moving to its upper position wrapping the lm around the package, and means on the elevator shifted by a package to positively release said releasable gripping means to release the leading edge of the lm.

18. In an automatic wrapping machine, a frame means on the frame for folding lm extending from the ends of the package to the underside thereof, and means for wrapping a length of iilm around the package prior to cutting of the film from a web of lm comprising, means mounting a supply roll of film, means on the frame guiding the web of lm to a package wrapping location, an elevator at said location movable between an upper position at the level of said lm folding means and a lower level, means on said elevator for releasably gripping the leading edge of the film to draw the film across the entry side of the elevator as the elevator moves to said lower level, means for pushing a package into said lm while moving the package onto said elevator, said elevator in moving to its upper position wrapping the lm around the package, a back-feed member disposed in a loop of lm in advance of said wrapping location, and means moving said member in timed relation with the elevator whereby as the elevator moves down to its lower level the member is moved up to avoid restraint on the lm and as the elevator moves up the member moves down to back feed the lm and either assist in tightly wrapping the ilm around the package or maintain the iilm relatively taut if no package has moved onto the elevator, and means on the elevator shifted by a package to positively release said releasable gripping means whereby lm pressure on the packaged material is lessened and the absence of a package will not release the leading edge of the lm.

References Cited UNITED STATES PATENTS 1,869,545 8/1932 Crafts 242-66 X 2,604,744 7/ 1952 Klimas 53-210 2,792,677 5/1957 Kilgard et al. 53-210 X 3,075,326 l/l963 Waite 53-39 X 3,170,274 2/1965 Roberts et al. 53-389 X 3,248,848 5/1966 Littleeld 53-210 TRAVIS S. MCGEHEE, Primary Examiner.

NEIL ABRAMS, Assistant Examiner.

U.S. Cl. X.R. 

